This is the 4187th most frequent Polish word.
cy
"Cy" in Polish is a particle used to introduce yes-no questions, equivalent to "whether" or "if" in English.
In this sentence, 'Czy' is used as an interrogative particle to introduce a yes/no question.
Czy wiesz, gdzie jest najbliższy sklep?
Do you know where the nearest store is?
'Czy' here functions as a conjunction to introduce an indirect question or a statement of wonder.
Zastanawiam się, czy w weekend będzie ładna pogoda.
I am wondering if the weather will be nice on the weekend.
'Czy' is again used as a question particle but in a negative question to seek confirmation or clarification.